If you have previously recommended this thread, you should see a tick / check mark on the recommend button. Click the tick to undo the recommendation (the tick may appear to change to a cross as you do this.) If you added a comment with your recommendation, you will need to delete that from your facebook wall separately.
I often wonder if the Nursery reviews on MN get loads of false hits, because I often click on them accidentally when I try to slide from "Talk" to the subcategory "Active" in the menu bar at top of page.
My fingers are one of my slimmer features. I never did this on the old app, or maybe extremely occasionally. The banner seems bigger and more sensitive. It happens when I am scrolling down. I suppose actually there's more need to scroll down as we don't have the pages. Which I miss!